As the band's name is "an organelle that generates most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy", I think this is the answer to your question: http://en.wikipedia.org/wiki/Caesium-137.

As the band's name is "an organelle that generates most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy", I think this is the answer to your question: http://en.wikipedia.org/wiki/Caesium-137.